Is the Sunnah to hold the feet apart or together when prostrating?

Firstly: 

With regard to the description of how the Prophet (peace and blessings of Allah be upon him) prayed, in detail, this has been explained previously on our site, in the answer to question no. 13340. For information on the evidence and a detailed discussion thereon, please refer to the book by Shaykh Muhammad Naasir al-Deen al-Albaani (may Allah have mercy on him) entitled Sifat Salaat al-Nabi sall Allahu ‘alayhi wa sallam min al-Takbeer ila al-Tasleem ka’annaka taraahu [available in English under the title: The Prophet’s Prayer Described from beginning to end as though you see it]. This is a useful book which in sha Allah will give you sufficient information about the evidence, as there is not enough room on our website to list all the evidence, just a summary thereof.  

Secondly: 

With regard to placing the feet together when prostrating, is the Sunnah is to place them apart, or to keep them together? The fuqaha’ differed concerning this matter and there are two views: 

1-

That it is mustahabb to keep them apart. This is the view of the majority of scholars who discussed this issue. They quoted as evidence the proof in the Sunnah that it is mustahabb to keep the knees and thighs apart when prostrating. They said: And the feet should follow them. So the basic principle is that they should be kept apart too. 

Abu Dawood (735) narrated that Abu Humayd (may Allah be pleased with him) said, describing the prayer of the Prophet (peace and blessings of Allah be upon him): “When he prostrated, he kept his thighs apart.” 

Al-Shawkaani (may Allah have mercy on him) said: 

The words “he kept his thighs apart” mean that he kept his thighs, knees and feet apart. 

The companions of al-Shaafa’i said: The distance between the feet should be a handspan. End quote. 

Nayl al-Awtaar (2/297). 

Al-Nawawi (may Allah have mercy on him) said: 

Al-Shaafa’i and his companions said: It is mustahabb for the one who is prostrating to keep his knees and feet apart. Al-Qaadi Abu’l-Tayyib said in his commentary: Our companions said: There should be the distance of a handspan between his feet. End quote. 

Al-Majmoo’ (3/407). 

2-

That it is mustahabb to put the feet together. Among contemporary scholars, this view was favoured by Shaykh Ibn ‘Uthaymeen and Shaykh al-Albaani (may Allah have mercy on him). 

Those who favoured this view quoted as evidence the report narrated by the Mother of the Believers ‘Aa’ishah (may Allah be pleased with her) who said: I noticed that the Messenger of Allah (peace and blessings of Allah be upon him) was not there and he had been with me in my bed. I found him prostrating, with his heels together and his toes turned towards the qiblah, and I heard him saying, “I seek refuge in Your pleasure from Your wrath, and in Your forgiveness from Your punishment, and in You from You; I praise you and I cannot praise You enough.”

Narrated by al-Tahhaawi in Bayaan Mushkil al-Athaar (1/104); Ibn al-Mundhir in al-Awsat (no. 1401); Ibn Khuzaymah in his Saheeh (1/328); Ibn Hibbaan in his Saheeh (5/260); al-Haakim in al-Mustadrak (1/352), and from him by al-Bayhaqi in al-Sunan al-Kubra (2/167). 

Al-Haakim said: This is a saheeh hadeeth according to the conditions of the two Shaykhs (al-Bukhaari and Muslim) but they did not narrate this version. I do not know of anyone who mentioned keeping the heels together when prostrating except what is in this hadeeth. 

Al-Dhahabi said in al-Talkhees: It meets their (al-Bukhaari and Muslim) conditions. 

Ibn al-Mulaqqin said in al-Badr al-Muneer (3/669): Its isnaad is saheeh. It was classed as saheeh by Shaykh al-Albaani (may Allah have mercy on him) in Asl Sifat Salaat al-Nabi sall-Allahu ‘alayhi wa sallam (2/736). 

Ibn Khuzaymah included this hadeeth in a chapter entitled: Chapter on keeping the heels together whilst prostrating. 

Al-Bayhaqi included it in a chapter in al-Sunan al-Kubra (2/167) entitled: Chapter on what was narrated concerning keeping the heels together whilst prostrating. 

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: 

What appears to be the case from the Sunnah is that the feet should be kept together, i.e., touching one another, as it says in al-Saheeh, in the hadeeth of ‘Aa’ishah when she noticed that the Prophet (peace and blessings of Allah be upon him) was not here, and her hand alighted on the soles of his feet which were held upright as he was prostrating. 

One hand could not alight upon both feet unless they were held together. 

That is also mentioned in Saheeh Ibn Khuzaymah, in the hadeeth of ‘Aa’ishah mentioned above: The Messenger (peace and blessings of Allah be upon him) was holding his heels together.  

Based on this, the Sunnah is for the feet to be kept together, unlike the thighs and hands. End quote. 

Al-Sharh al-Mumti’ (3/169) 

And Allah knows best.